Monday, June 04, 2012

Proof That Greenland's Glaciers Were Melting Faster 80 Years Ago

There's much scientific interest in the Greenland ice sheet, as unlike most of the Arctic ice cap it sits on land: thus if it were to melt, serious sea level rises could occur (though the latest research says that this doesn't appear to be on the cards).

It's difficult to know exactly what's happening to the Greenland ice in total and very different estimates have been produced in recent times. However Professor Box says that many glaciers along the coasts have started retreating in the past decade.

It now appears that the glaciers were retreating even faster eighty years ago: but nobody worried about it, and the ice subsequently came back again. Box theorises that this is likely to be because of sulphur pollution released into the atmosphere by humans, especially by burning coal and fuel oils. This is known to have a cooling effect.

Unfortunately atmospheric sulphur emissions also cause other things such as acid rain, and as a result rich Western nations cracked down on sulphates in the 1960s. Prof Box believes that this led to warming from the 1970s onward, which has now led to the glaciers retreating since around 2000.

Other scientists have said recently that late-20th-century temperature rises in the Arctic may result largely from clean-air legislation intended to deal with acid rain: some have even gone so far as to suggest that rapid coal- and diesel-fuelled industrialisation in China is serving to prevent further warming right now.

Still other scientists, differing with Prof Box, offer another picture altogether of Arctic temperatures, in which there were peaks both in the 1930s and 1950s and cooling until the 1990s: and in which the warming trend which resulted in the melting seen by Rasmussen's expedition actually started as early as 1840, before the industrial revolution and human-driven carbon emission had even got rolling. In that scenario, variations in the Sun seem to have much more weight than is generally accepted by today's climatologists.


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